St. Piran's Day is celebrated on March 5th each year in Cornwall, England. It honors St. Piran, the patron saint of Cornwall, who is believed to have brought Christianity to the region in the 5th century. The day is marked by various festivities, including parades, music, and traditional Cornish food. The celebration often features the display of the Cornish flag, which is black with a white cross. Many people participate in community events, showcasing their pride in Cornish culture and heritage. St. Piran's Day serves as a reminder of the region's history and its unique identity within the United Kingdom.